Take these guides with a grain of salt! They're not the holy bible of mapping - a lot of these are still opinions. Not everyone's shares the same vocabulary either (what on earth is "drumsticking"?) My advice is to follow these rules until you're comfortable with your skills, and then get creative, experiment and innovate!

Publishing Songs

Please do not upload WIPs to BeatSaver! It's hard to tell which maps aren't finished in game, and anyone who plays your WIP without practice mode will create a new leaderboard for that map. Uploading to BeatSaver should be akin to putting it on store shelves - that is, it's your final product. To share for playtesting, we encourage you to use the #testplays channel in the discord and get feedback to improve your map!

Editors

The official editor has not been released.
All custom maps are being made using the community built map editors.
There are currently 3 editors. All export the same files, but offer different workflows.

Mediocre Mapper

While most people use this editor because it's by far the most feature rich of the 3, this is still first and foremost squeaksies' personal editor. It's filled to the brim with memes and inside jokes, and he doesn't give a flying heck what you think about it.

Where are custom maps saved?

"Your audio file name is wrong" message in the Edit Saber

The 3D Editor only supports .ogg files. You have to convert your file to Ogg Vorbis using a converter, such as Audacity.
If you simply change the file extension to .ogg, it will not work.

How do I delay a song so that it doesn't start right when the level loads?

Currently this isn't possible in Beat Saber or the editors. For now you have to edit the song in an audio editor (such as Audacity) to add silence at the beginning of the track.
Check out Kolezan's Song/Audio Editing Guide for instructions.

I'm having issues uploading the map to BeatSaver, it says the format is invalid but everything looks right.

If you have Windows file extensions turned off, then you might have unknowingly saved your files with names like cover.jpg.jpg. To turn off file extensions in Windows, see the following image:

I want to double the BPM of my song, is there an easy way to do that?

Here is a Python3 Script that will multiply the BPM and _time values in your JSON file by any given factor.